Adolescents diagnosed with Hodgkin disease (HD) usually have an excellent clinical outcome; however, therapy is related to late sequela. Female survivors are at greatest risk for secondary malignancies, with breast cancer being the most common. While the occurrence of secondary breast cancer is associated with radiation therapy, the mechanism is not understood. This study will use microarray technology in the analysis of peripheral blood leukocytes to compare the gene expression between pediatric HD survivors who have and have not developed secondary breast cancer. The Affymetrix GeneChip Human Genome U133 Plus 2 Array will analyze the expression level of over 47,000 transcripts and variants, including 38,500 human genes. Differential expression between the two groups will be done with the GeneChip Human Mapping 100K Set in exploring an association between expression and genotype. Thirteen patients with secondary breast cancer will be evaluated and compared with 26 patients who have not developed secondary breast cancer. Bioinformatics and statistical analysis will be completed between and within groups. This study will offer insight to the molecular mechanism of disease and development of a potential risk model. [unreadable] [unreadable] [unreadable]